LRBT are probably the weakest of the leman rus (tied with the vanquisher for most sucky) due to having to snap fire all its weapons. A single S8
AP 3 blast doesn't really compare to a demolisher or eradicator (which can actually fire it's bolters normally).
So for
HQ I think you are looking at pask in punisher + 1 or 2 demolishers or eradicators.
I love putting
pcs with 4 flamers into vendettas, very cheap and pretty good.
Knight is a good addition. Far better than a bane blade (and cheaper). If you want a superheavy battle tank, take the one with the S10
AP 2 ignores cover cannon (the only one they banned from
BAO
I'm also a big fan of power axe and meltabomb blobs (with priest)